In many areas of society, complex systems are controlled by human operators relying on information provided by instruments and gauges which monitor the system. These systems include power generation plants, nuclear reactors, commercial aircraft, heavy equipment and trucks, the space shuttle, and will expand to include such systems as the International Space Station. Mistakes in the operation or design of these systems can compromise the safety of the operator, crew, passengers, or the public at large. Representative design errors include gauges which can not be read from the operator's normal position, controls which can not be reached from the operator's normal position, and controls which can not be reached while simultaneously viewing the necessary gauges which are providing feedback. Because of the consequences of such errors, the design and layout of control panels is critical.
Instrument and control panel design is a complex and often lengthy process which must consider many factors including readability of gauges, viewing angles to gauges, access to controls, feel and range of movement of the controls, ergonomics, and resistance to environmental factors such as vibration, dust, water, etc. Typically, several iterations of a design will be tried before the final design is approved. Each iteration may be very expensive. This expense may limit the number of iterations allowed for during the design to less than that needed from a technical standpoint. However, re-design of a faulty control system which has already been fielded is far more expensive. For example, wiring looms, air ducts, and mechanical controls may have been custom designed for a specific layout and would have to be redesigned if an instrument needs to be relocated.
Design iterations are most expensive where the real instruments and gauges from the final system are used. This equipment is expensive and not adapted to ease of reconfiguration. Prototyping is often used to reduce the cost of design iterations. Prototypes can range from scale or full size drawings of the control panel to mock-ups with dynamic displays to fully interactive simulations of the complete system. Each of these approaches trades cost against the fidelity of the representation. The better the fidelity, the more accurate the information gathered from the use of the prototype. Static drawings are valuable for initial decisions but are inadequate for evaluating operational scenarios. Interactive simulations are capable of providing very accurate data on operator response times, decision making, and the ability to accurately control the system. Alternate panel layouts can then be compared to optimize the design. The greater the cost savings for each iteration the larger the number of alternatives that can be explored, and the greater the likelihood that a safe system will be developed. The need, therefor, is for inexpensive, easily reconfigured, yet high resolution prototyping capabilities.
High resolution simulations are also valuable for training purposes. The human operator(s) can be presented with a variety of both normal and emergency situations to which they must respond as they would with the real system. Sufficient training time can develop automatic, calm responses to "once in a lifetime" situations of a critical nature, resulting in significant savings of life and damage when the situation does arrive. For this type of training, the fidelity of the simulation is critical. Gauges and controls must be located where the operator expects them to be and controls must respond exactly as the real controls so that the operator does not have to look away from the instruments to locate a control. This is true both while training and so that the experience gained will directly transfer to the operational system when the trainee is on the job. While these concerns can be addressed for some non-emergency training by performing it on the operational systems, this is usually not cost effective.
A variety of approaches to prototypes and simulations have been used. The highest fidelity, and most expensive is to use the real instruments in a design mock-up. FIG. 1 shows a representative aircraft instrument panel prototype as might be applicable to a regional airline. Gauges, 202A, are mounted to an instrument panel, 200A, in the same layout as in the actual aircraft. FIG. 2 shows a top view of the panel illustrating the corresponding spacing of the instruments behind the panel. The instruments are often very expensive, having been designed and built for the final environment, such as an airline cockpit. The cost is further increased by the necessity to keep spares on hand. Implementation of the mock-up can also be expensive as the environmental needs of the instruments must be met. This approach may require high voltage power supplies, high capacity cooling, and complex data inputs and outputs which emulate the real-world systems. In some situations, simulated electromechanical instruments may be available, which reduce the cost. However, they may not be readily available and do not alleviate the other concerns. This approach is not feasible where a system is being designed that will be using new instruments or new instrument designs. In these situations the real instruments are not yet available.
One approach to avoid using real instruments is to use computer displays, such as CRT screens, to generate the instrument images. The images are then masked by a physical face plate to provide the appearance of an instrument panel. FIG. 3 shows a simulated instrument panel corresponding to the mock-up of FIG. 1. FIG. 4 illustrates the placement of the CRT screens behind the panel. FIG. 5 provides a cross-section through the CRT showing the detailed positioning as it would appear from a top view. The faces of the gauges, 202B, are displayed on the CRT screens, 204, positioned immediately behind the panel, 200B.
Several problems exist with this approach which directly impact the fidelity of the simulation. Primary of these is the constraints imposed by the size and shape of the display screen, 206 and 208. Gauges must be arranged so that they appear entirely within the bounds of the screen. In the example panel, it was possible to maintain the real layout of the gauges on the left-hand screen, 206. However, screen 208, required altering the position of certain gauges. Unit, 210, is a radio device which must be represented by a real unit in order to provide the communications functionality of the unit. As such, it could not be modeled on the CRT and was placed outside the boundaries of the display. However, gauges, 212, were to be modeled on the CRT screen and had to be placed within the screen boundaries. This combination resulted in the positions of instruments 210 and 212 being shifted relative to each other to allow their simulation. This layout no longer matches the real layout, reducing the fidelity. It was also necessary to reduce the size of gauges, 212, to fit them onto the screen without also moving gauge, 214. In some situations, this will have far reaching effects as other gauges are then reduced in size to maintain proper relative sizes between the gauges. Alternatively, the decision could be made to make a device non-functional to enable the simulation as a whole. Here, device, 216, is represented on the screen, but is non-functional. This also impacts the fidelity of the simulation as this functionality is not available to the operator (pilot).
A second significant problem is the space at the edge of the CRT screen, 218, which is unusable for display purposes. This consists of an unusable portion of the screen itself, plus the space occupied by the support structure (housing or shell) enclosing the screen. While this space can not be used to display gauges, it does occupy physical space behind the instrument panel. This results in artificial gaps, 220, in the instrument panel in which no instrument can be located. A similar problem exists where the dimensions of the display must be accommodated. An example occurs on the right side where the lower edge of the CRT, 222, extends below the normal lower edge of the instrument panel. This was necessitated by the placement of the radio units, 210, at the top of the panel, above the CRT screen.
Another limitation of this approach is that it is impractical for use with isolated instruments, 224 and 226, and impossible to use with isolated gauges, 228, which are surrounded by functioning instruments, 230, which take up space behind the panel.
A further problem with this approach involves the off-angle viewing of the gauges as illustrated by FIGS. 6-8. FIG. 6 shows a representative gauge, 234, as it would appear face-on. From this angle, the CRT simulation can appear identical to the real gauge. FIG. 7 illustrates a real gauge, 234A, as it would appear from an angle. This is how a copilot might see a gauge positioned in front of the pilot or how a power plant operator might view a gauge positioned on an adjacent sub-panel. Because the face of this real gauge is aligned essentially with the surface of the instrument panel, it is only slightly obscured by the rim of the gauge. FIG. 8 illustrates how the simulated gauge, 234B, might appear when represented on a CRT screen. In the worst case scenario where the gauge is located in an edge position, 232 in FIG. 5, the image, 202B, is actually located well behind the plane of the instrument panel due to the thickness of the glass and the curvature of the screen. The obscuration becomes significant, blocking almost one half of the gauge.
The use of CRT screens to generate the gauge images also causes a problem with the representation of related controls. FIG. 9 illustrates a generic gauge, 236A, with an integral adjustment knob, 238A. As shown in FIG. 10, the knob connects to an adjustment mechanism which is within the housing of the gauge. Where the gauge is simulated by a CRT screen, FIGS. 11 and 12, the control knob, 238B, must be implemented with a separate mechanism. Because the CRT screen is located close to the instrument panel to provide the best image presentation, there is no space behind the panel for the control mechanism. This requires that the control be housed in front of the instrument panel, 240B. In order to accommodate the control circuitry and requisite wiring connections, this housing may be quite large. In existing aircraft flight simulators, the diameter of the housing may be as large as one-half the diameter of the gauge. This impacts the fidelity of the representation by altering the location of the control in two ways. First, the control protrudes significantly from the front of the panel. Secondly, the control has to be moved away from the center of the gauge so that the housing does not intrude on the face of the gauge. Both of these changes result in a control which is positioned differently than in the real system. Where the control would be operated by touch this can be an important difference. In addition, moving the control laterally effectively increases the size of the gauge, requiring increased spacing from adjacent gauges. The use of low profile or smaller controls can help alleviate the above problem but usually increases the cost and introduces further fidelity problems as the feel of the control, and possibly the range of movement, is different than that of the real control.
Several techniques have been used to reduce the problems posed by computer display simulations. The use of flat screen displays eliminates the curvature of a conventional CRT screen and helps reduce the amount of obscuration present, but does not alleviate any of the other problems. In addition, large flat screen displays are significantly more expensive that conventional CRT displays.
Plexiglas inserts have been used to provide the illusion that the instrument face is at the correct location relative to the instrument panel. However, since it does not actually alter the location at which the image is displayed, it does not solve the obscuration problem. It has no effect on any of the problems.
The use of full diameter fiber optic guides (or conduits), FIG. 13, has been suggested although no actual implementations of the technique are known. The guides, 242, would transmit the image, 202B, from the face of the CRT screen, 204, to a position corresponding to the face of the real gauge. This would solve the off-angle viewing problem since the image of the gauge would be in the correct plane. However, these full size guides are very expensive to manufacture at the requisite quality and the diameters required (3 inches or more) may be beyond current production capability. Additionally, the full diameter guides are quite heavy, requiring substantial support structure. This technique does not solve any of the problems discussed above other than off angle viewing. There is still a direct one-to-one correspondence between the location of the gauge images on the screen and the panel location of the gauges. Space is still lost at the edges of the screens and gauge positions must be adapted to the screen shape. The problem with protruding controls is not solved because the full diameter guides do not allow sufficient room between them to position a control behind the panel.
Fiber optic techniques have also been used in other fields to solve viewing problems. Fiber optic guides are used in the medical and photographic fields to transmit an image from where it can be perceived to where it can be viewed or recorded. Most often this involves coupling a lens to one end of the guide and a camera to the other end. The lens, which is significantly smaller than the camera, can then be inserted into a small opening allowing the image to be remotely recorded or viewed. This technique is perhaps most widely known for its use in arthroscopic surgery and is also used for machine inspection via small access ports.
Fiber optic tapers are used to magnify or minify (reduce) images for viewing. One common application is to compress a received image and transfer it to a CCD imaging device. Arrays of tapers are used to provide line scans and 2-D tiled arrays can be used to capture larger images. Tapers are also used to enlarge images in the VVS-2 night drivers' viewer used in Army tanks.
There is a need for a method of prototyping or simulating instrument display panels which provides increased flexibility in the positioning of instruments and gauges. Preferably this method would allow for computer generation of the instrument face, allowing rapid alterations to their appearance. It should be possible to relocate the simulated instrument within the control panel with minimal time and cost. Preferably the method should impose no artificial constraints on the location of the instruments. There should be no lost space due to computer display housings. It should be possible to position a simulated gauge adjacent to, or, ideally, surrounded by other devices which extend a significant distance to the rear of the control panel. There should be no off-angle obscuration which exceeds that of the real gauges. It is also preferable that a control can be inset behind the instrument panel immediately adjacent to a simulated gauge in the same relative position as the real control on the real gauge. The cost of this prototyping technique should be sufficiently less than the use of real instruments to enable multiple iteration prototyping and design refinement.